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This winter, tens of thousands of birdwatchers across North
America will bundle up and brave the elements, all in the name of
science.

The National Audubon Society's 114th annual
Christmas Bird Count begins Saturday (Dec. 14). Volunteer
citizen scientists in all 50 U.S. states, all Canadian provinces,
and parts of Mexico, Latin America, the Caribbean and the Pacific
Islands are set to take part in the yearly tradition, armed with
bird guides, binoculars and checklists.

The annual count is the longest-running census of bird
populations, and is used to help scientists assess the health of
different species, said Geoff LeBaron, director of the Christmas
Bird Count (CBC).

"We try to look at the trend data to understand what's going on
in the big picture," LeBaron told LiveScience. "Are species
increasing, declining, or shifting their ranges? These are some
of the larger-scale analyses we do with CBC data." [ Quest
for Survival: Incredible Animal Migrations ]

Participation in the count, which runs from Dec. 14 through Jan.
5, 2014, has been steadily growing, he added.

"In our first Count, in 1900, there were 25 counts and 27 people
involved," LeBaron said. "Last year, there were 2,369 different
Christmas Bird Counts, and we had over 71,000 observers."

This season, birdwatchers may be treated to sightings of
snowy owls for the third year in a row, Audubon officials
said. These large, majestic birds — popularized in the Harry
Potter novels and films as Harry's pet owl, Hedwig — have already
been spotted as far south as North Carolina and the island of
Bermuda.

"We're seeing record movement of snowy owls in the Northeast so
far," LeBaron said. "For three years in a row, we've seen this
southward movement of snowy owls, and in places where it's
rare to see these birds. It's going to be really interesting how
this plays out."

Snowy owls are an irruptive species, which means their population
growth is characterized by unpredictable booms and subsequent
crashes. When food is scarce up north, these Arctic predators fly
south in search of sustenance. But, scientists are scratching
their heads over the recent spike in sightings.

"It's not unusual that there's a flight of snowy owls — it's part
of their biology, and it's something that happens every three to
five years," LeBaron explained. "What's unusual about this is
that it's happening three years in a row."

Weeks before the start of the Christmas Bird Count, snowy owls
had already been reported in New Jersey, Pennsylvania,
Massachusetts, Virginia and New York.

This year, LeBaron plans to take part in two counts: one in Rhode
Island and one in Massachusetts. He encourages people of all
skill levels to participate in local counts, including beginners
with no previous birdwatching
experience.

"It's a great way for new birders to learn more about it," he
said. "It's also great for kids, and we've seen a lot of kids
turn into the fabulous birders very quickly by participating in
the counts. Plus, there's always an element of beginner's luck."